For the first time ever, just over 1 billion smartphones shipped to vendors worldwide in 2013, double the number of just two years earlier, IDC said late Monday.

If you had any doubts about the popularity of smartphones, new numbers suggest they've notched a significant milestone. The global smartphone market topped 1 billion shipments for the first time in 2013, covering about one-seventh of the world's population, according to research by IDC.

Smartphone shipments were up 38.4% in 2013 from 725 million units in the previous year, according to data from IDC's Worldwide Quarterly Mobile Phone Tracker.

In 2013, there were 1.82 billion mobile phones shipped, which includes smartphones, an increase of 4.8% from 1.73 billion in 2012.

Samsung continued its dominance in 2013 with 31.3% market share in smartphones compared to Apple's 15.3%. The top two vendors were followed by Huawei at 4.9%, LG at 4.8%, and Lenovo at 4.5%, according to IDC.

"Of the two, I have to say that low cost is the key difference maker. Cheap devices are not the attractive segment that normally grabs headlines, but IDC data shows this is the portion of the market that is driving volume. Markets like China and India are quickly moving toward a point where sub-$150 smartphones are the majority of shipments, bringing a solid computing experience to the hands of many."

The IDC numbers, released the day Apple reported record-high sales of 51 million iPhones in the quarter to Dec. 28, are roughly in line with data from another research firm, Strategy Analytics.

It pegged 2013 global smartphone shipments at a record-high 990 million units, up 41% from over 700 million in 2012. The rate of growth was down slightly from 43% in 2012 due to the already high penetration in big markets like the U.S., the research firm said.

The market shares it reported roughly matched those from IDC, with Samsung at 32.3%, Apple at 15.5%, Huawei at 5.1%, LG at 4.8% and Lenovo at 4.6%.

"Samsung and Apple together accounted for almost half of all smartphones shipped worldwide in 2013," Linda Sui, senior analyst at Strategy Analytics, said in a release.

The two companies kept their grip of the market by large marketing budgets, extensive distribution channels and attractive product portfolios, but there is now more competition coming from second-tier smartphone brands, Sui said. Huawei, LG and Lenovo each grew their smartphone shipments around two times faster than the global industry average and captured a combined 14% market share, according to Sui.

"Huawei is expanding swiftly in Europe, while LG's Optimus range is proving popular in Latin America, and Lenovo's Android models are selling at competitive price points across China. Samsung and Apple will need to fight hard to hold off these and other hungry challengers during 2014," Sui said.